I know, seriously...that's such an odd stay, and, a complete waste of aircraft utilization. They could send the plane back 2 hours later after arrival and the aircraft would arrive in SFO in the early evening, great time for providing overnight red eye conntections to the east coast (you'll be tired as hell anyway so who cares).

It's pretty standard for United's SFO-China flights. They want the flights timed to leave SFO westbound in the early afternoon, along with all their other Asia-bound flights, so they can benefit from all the connections. But, by the time the planes go to China, and then turned around, they wouldn't leave the Chinese cities until late at night (after 1900-2000 local) and thus wouldn't get back to SFO until early evening (1700-1800 local), which is an absolute waste for connections (most of which are, again, timed for all of the other inbound Asia arrivals which get into SFO around 0900-1200). The plane would then have to RON in SFO until the next day, before heading back out again to China.

Thus, it makes sense to just RON the plane at the Chinese stations and send them out the next morning.

Besides, either way, regardless of whether the plane RONs in SFO or in China, the schedule would still require 2 aircraft to keep a daily rotation. So, in other words, it makes no difference where the plan spends the long layover: whether SFO or PEK/PVG/CAN, it still takes the same 2 planes per route. In that case, why not time the flights to maximize connections at SFO which is the hub that is - after all - supposed to be designed specifically to capture connections?

With the restrictions on service to China, is that only for USA-China flights? Could this plane go onto another destination? I'd agree that 17 hours is a long time. Maybe United can get some maintenance done on the plane since they are contracting it all out anyhow.

It's pretty standard for United's SFO-China flights. They want the flights timed to leave SFO westbound in the early afternoon, along with all their other Asia-bound flights, so they can benefit from all the connections. But, by the time the planes go to China, and then turned around, they wouldn't leave the Chinese cities until late at night (after 1900-2000 local) and thus wouldn't get back to SFO until early evening (1700-1800 local), which is an absolute waste for connections (most of which are, again, timed for all of the other inbound Asia arrivals which get into SFO around 0900-1200). The plane would then have to RON in SFO until the next day, before heading back out again to China.

Thus, it makes sense to just RON the plane at the Chinese stations and send them out the next morning.

Besides, either way, regardless of whether the plane RONs in SFO or in China, the schedule would still require 2 aircraft to keep a daily rotation. So, in other words, it makes no difference where the plan spends the long layover: whether SFO or PEK/PVG/CAN, it still takes the same 2 planes per route. In that case, why not time the flights to maximize connections at SFO which is the hub that is - after all - supposed to be designed specifically to capture connections?

Actually come to think of it you make a good point about this. It would still require 2 aircraft.